Please note that recent versions of the Developer's Custom Fields plugin may have created minor issues with single checkbox values. For more information, and to tidy up the database, make sure you visit the Custom Fields database tools page and run the cleanup tool there.

If this is the first time you've used this plugin, or you don't think you'll have a problem with this, dismiss this notice.

this notice appearing on edit pages.. even for editors.. what can editors do about it? how can i disable it?

If you don't think the issue described applies to you, you should be able to click "dismiss this notice". Or, you can click to go through to the database clean-up tool. Run this (after backing up your data!) and the notice will disappear. If you have any problems with either of these approaches, let me know.

Yeah its really not problem for me.. Problem is i am preparing to open a special network site that people can register and create their websites, i dont want to bother them with those msgs..
Any remove_filter or something for prevent it?

This is a one-off notice, so if you've dismissed it, it shouldn't appear for anyone else. Let me know if it does. If there's ever anything else in the future, I'm assuming as the admin you will be installing the new plugin version, and you will be able to dismiss any notices before anyone sees them?

Of course, if you check the code you'll find the add_action that you can remove if you really want to.

However, I'd advise against this. Any notices output like this will be important things for admins to read. If there's an upgrade in the future that unfortunately includes changes that may be a problem for some installations, this is how admins will be made aware of the necessary steps to avoid problems. If you remove the admin notices action, you might miss an important notice, and end up with something not working! It's a remote possibility, and of course I'm doing my best to avoid changes that might cause problems, but if it's necessary, I will include a notice with a fix.

Admins should install upgrades, of course. So, admins should see these notices on upgrading, if there are any - they need to. And they can dismiss them straight away if there's no problem - and no one else sees the notice.